1. Field of the Invention
The present invention relates to a laser diode array unit, and more particularly, to a laser diode array unit for use in laser beam scanning optical devices and the like.
2. Description of Related Arts
Recently, for use as a light source device in a laser beam scanning optics arrangement, laser diode arrays having a plurality of light emitting points have been receiving attention. For use with such laser diode array, monitoring mechanisms for monitoring the emission intensity of light emitting from the laser diode array itself have been proposed including one such that a half mirror is used to direct monitoring light onto a photoreceptor element as described in Japanese Patent Application Laid-Open No. 6-164056, and another such that an aperture having a polished surface is used to conduct monitoring light onto a photoreceptor element as described in Japanese Patent Application Laid-Open No. 6-164070.
The above cited arrangements are such that the mechanism for monitoring the intensity of light is provided outside the laser diode array package. Whilst, there has also been proposed an arrangement such that the intensity monitoring mechanism is provided within the laser diode array package. In such an intensity monitoring mechanism, laser beams emitted from individual light emitting sources are separated by means of a barrier so as to be prevented from overlapping, and the separated laser beams are separately monitored by photoreceptor elements corresponding to respective laser beams which are provided within the laser diode array.
However, of these prior art intensity monitoring mechanisms, those of the type in which the monitoring mechanism is provided outside the laser diode array package are such that the light emitting sources in the laser diode array are spaced a small distance from each other, say, on the order of several tens of .mu.m, so that laser beams emitted from respective light emitting sources overlap one with another, which fact makes it difficult to separately monitor the intensity of light with respect to laser beams emitted from respective light emitting sources. Therefore, such monitoring mechanism could only monitor a total intensity of light of plural laser beams.
Those of the type in which the intensity monitoring mechanism is provided within the laser diode array package involve a problem that the laser diode array itself is complex in construction and higher in cost. Another problem is that since the construction of the laser diode array requires provision of a barrier or the like, it is impracticable to reduce the distance between the light emitting sources.